RRA model sinks into ground

[Aya Alwan]

Hello,

I'm using Opensim 4.5 to run RRA and CMC on a walking trial. The model sinks into the ground as if GRF data don't exist. I'm attaching the GRF, IK, and model files. I use the default actuators, constraints, and tasks files from gait2354 model. Could you help resolve the issue? I tried the recommendations from previous posts and it still falls into the ground. I would highly appreciate it if someone could check my GRF file.

Thank you,

Aya

[Mohammadreza Rezaie]

Hi, looking at your force file, there are two redundant lines after endheader, and you need to remove them.

Screenshot 2024-07-15 093909.jpg (38.88 KiB) Viewed 1268 times

Hope this helps.

[Aya Alwan]

I did resolve this issue after posting the thread. The original problem is still there. Thank you though!

[Mohammadreza Rezaie]

Another issue I just found is that the GRF must be applied to the calcn_r (right side) and calcn_r (left side) bodies rather than the ground. This could be adjusted directly in the XML file or in the GUI:

Screenshot 2024-07-16 095117.jpg (73.43 KiB) Viewed 1163 times

Hope this helps.

[Aya Alwan]

Hi Mohammadreza,

I must have overlooked that. It helped! Thank you!! In terms of metabolic cost. I get about 500 Joules as a result from the "integrate" operation for the Umberger metabolic probe (CMC results). If I divide the value by duration (0.7 seconds) and weight (63 kg), I get about 11 W/kg. If I take the average metabolic cost results from the "value" operation and I integrate the total metabolic cost offline, I get 6.9 W/kg. Both do not seem to be reasonable values for someone walking on a treadmill at a 0.8 m/s speed. Is there something I'm missing? why does the integrate method in OpenSim provide different results from my offline integration?

Thanks again!